It is estimated that, in the United States, nearly 52% of the total population has some chronic health condition. There is sufficient evidence from the literature and nursing practice to substantiate that long-term health impairments have a high risk of being a major stressor on the family system. Yet, not all families deteriorate under this persistent stress. What are those key factors that facilitate the "healthy" functioning of the family system and the well-being of the individual members in the situation of long-term health problems? One major factor recognized as essential to stressful life events is social support. Yet, while it can be demonstrated that social support is essential to the maintenance of health and the recovery from illness there is a lack of agreement about the definition of social support and a lack of knowledge as to how it operates to reduce stress. The goal of this research is to further examine the function of social support in helping families to adapt to long-term illness. Specific aims are to: a) test the stress buffering mechanism of social support; b) assess the relative contribution of other exogenous variables, e.g., length of illness, family characteristics, etc. and social support to the level of family functioning; c) investigate the cost/reciprocity components of social support; and d) begin a longitudinal assessment of a group of families with respect to their level of support and the impact of social support and other relevant variables on their well-being by retesting a group of families from a previous study. Data will be collected using mailed questionnaires to 180 married couple families and 60 single parent families in which one of the adult members has multiple sclerosis. Data will be analyzed using appropriate bivariate and multivariate techniques, principally multiple regression, to address the issues in each of the aims. This study will contribute to the knowledge base of how families deal with a long-term illness and will allow for further exploration of theoretical and empirical issues related to the concept of social support.